Preheat oven to 325°F. Grease and flour a 10-inch tube pan.
Melt candy bars and butter, stirring frequently, in large, heavy Dutch oven over low heat. Remove from heat and stir in sugar.
Combine egg yolks, buttermilk and baking soda in small bowl until blended.
Combine flour and salt in another bowl. Add to candy mixture alternately with buttermilk mixture, beginning and ending with dry ingredients. Stir in pecans.
In clean mixer bowl, beat egg whites until stiff but not dry. Fold into batter. Pour into prepared pan.
Bake 1 1/4 hours or until set and cake pulls away from sides of pan. Cool on wire rack 15 minutes. Unmold and cool completely.
Melt chocolate in top of double boiler over simmering water. Spread over cooled cake.
Makes 16 servings.
